Question 648242


{{{1/R= 1/3 +1/4}}}

{{{1/R= (1*4 +1*3)/(3*4)}}}

{{{1/R= (4 +3)/12}}}

{{{1/R= 7/12}}}...cross multiply

{{{1*12= 7*R}}}

{{{12/7= R}}}